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题名	低密度水泥固井的井孔声场及其在水泥胶结质量评价中的应用
作者	陈德华
学位类别	博士
答辩日期	2007-06-11
授予单位	中国科学院声学研究所
授予地点	声学研究所
关键词	低密度水泥 水泥胶结质量评价 声波测井 数值模拟 实验测量
其他题名	Acoustic wave fields in cased boreholes with low-density cement and its application in cement bonding evaluation
学位专业	声学
中文摘要	本文利用二维谱离散波数法和有限差分法模拟计算了套管井的井孔声场，考察了固井界面的胶结状况、水泥环的声学性质和厚度、套管的几何尺寸以及仪器的偏心程度等对井孔声场的影响。数值结果表明，套管井声波测井中的套管波幅度随水泥密度的增大而减小，且采用低密度水泥和常规密度水泥固井时所得到的套管波幅度相差非常大。套管尺寸参数和仪器偏心度的变化也会对井内的套管波的传播造成影响。当套管内径不变而壁厚增大时，套管波的到达时间不变而幅度增大；当套管壁厚不变而内径增大时，套管波的到达时间延后、幅度减小。对油田实际生产中所使用的不同型号的套管，在水泥环厚度保持不变的情况下，在大直径套管中所得到的套管波相对幅度也要大。另外，仪器居中时所接收到的套管首波的幅度最大，随着偏心距的增大，波列中套管首波的幅度逐渐减小，但其到达时间却越来越早。 在理论研究工作基础之上，本文采用3:1的缩尺比例进行了模拟实验。在常温常压条件下，对水泥浇注后整个凝固过程进行超过70小时的动态监测，测量了套管波幅度随水泥凝固时间的变化，研究了不同密度、不同配方的水泥对套管首波幅度的影响。结果表明，水泥浇注后6小时以内，套管波幅度随水泥凝固时间的延长快速增大。当时间继续增大，套管波幅度逐渐降低，最终趋于平稳。平稳后套管波的相对幅度随水泥密度的变化规律与理论计算结果基本一致。对同一设计密度的水泥，当配方不同时，井内测到的套管波幅度也会发生变化。为改善固井水泥的胶结性能所添加的膨胀剂及低密度增强材料都会使套管波幅度降低，其中低密度增强材料的影响比膨胀剂的更大些。因此，根据声波幅度评价油井固井质量时，既要考虑水泥密度变化的影响，也要考虑水泥配方的影响。采用低密度的泡沫水泥固井时，水泥浆密度的波动可能会引起套管波幅度的较大变化。由于泡沫水泥浆含有气体，此时测量得到的套管波幅度不稳定。如果采用主要依据声波幅度的水泥胶结测井(CBL)或声波变密度（VDL）等常规的方法来进行泡沫水泥胶结质量的评价，在测井资料的准确解释方面会存在的困难，甚至会出现错误，此时需要结合超声扫描测井等其它的方法来进行固井质量评价。上述研究结果为油田采用低密度水泥固井时建立油井固井质量评价的解释新标准提供了重要依据。
英文摘要	Acoustic wave fields in cased boreholes are simulated by using a two dimensional discrete wavenumber method and a finite difference method in this dissertation. The effects of cement bonding conditions, acoustic properties and thickness of cement annulus, casing size, and tool eccentricity, on the acoustic field are investigated. Numerical results show that, the amplitude of casing wave (CW) in acoustic logging waveforms in a cased borehole with low-density cement is much greater than that of the normal density cement. Casing size and tool eccentricity also influences the propagation of the CW. As the thickness of the casing increases while its inner diameter keeps as a constant, the arrival time of the CW remains unchanged and the amplitude increases. And when the inner diameter of the casing with a constant thickness increases, the arrival time of the CW delays and the amplitude decreases. The relative amplitudes of the casing wave (RACW) show a higher value in the casing with a larger inner diameter for the cement annulus with the same thickness. In addition, the CW reaches its largest amplitude as the tool is centralized in the casing. It will have small amplitude, and will advance in the arrival time when the tool increases its eccentricity. Based on the theoretical studies, the simulation experiments with the scaled ration of 3:1 are conducted. Under the condition of the normal temperature and pressure, the amplitude of the CW in the cased hole are monitored for more than 70 hours after the cements is injected and begin to concrete. The effects of cement densities and compositions on the amplitude of the CW are studied experimentally. It is shown that the amplitudes of the CW greatly increase within the first 6 hours, and, afterwards, they decrease gradually during the curing periods. Finally the CW reaches to stable amplitudes. The experiment results of final stable amplitudes of the RACW are in agreement with the numerical results qualitatively. As for the cement with the same density but different compositions is concerned, the amplitudes of the CW measured in cased holes are different. The amplitudes of the CW decreases as the dilated material and intensifier are added into the cement slurry in order to promote its bonding and curing performance, and the intensifier has greater influence than the dilated material. Therefore, not only the effect of densities, but also the cement compositions should be considered in cement bonding quality evaluation by using the acoustic amplitude logging. When the foamed cement is used for cementation, a small fluctuation in density could cause a great variation in the acoustic amplitudes, and the measured amplitudes of the CW is not very stable because of the foamed gas bearing slurry. If only the traditional evaluating methods mainly based on the acoustic amplitude, such as cement bond log (CBL), and/or variable density log (VDL), are used, there are difficulties in the data explanation because of the discrepancy between the measured acoustic amplitude and the expecting standard, and thus an incorrect decision on squeeze cementing could be made. In this case, it is necessary to combine other logging data, such as ultrasonic scanning logging, to evaluate the bonding quality. The present studies provide an important reference for a new interpretation standard in cement bonding quality evaluation with low-density cements.
语种	中文
公开日期	2011-05-07
页码	123
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/144]
专题	声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文
推荐引用方式 GB/T 7714	陈德华. 低密度水泥固井的井孔声场及其在水泥胶结质量评价中的应用[D]. 声学研究所. 中国科学院声学研究所. 2007.

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